The invention relates generally to methods and apparatus related to gravel packing with a tool that maintains a desired pressure in a target wellbore section.
Techniques are well known in the oil and gas industry for controlling sand migration into wells penetrating unconsolidated formations by gravel packing the wells. Sand migration and collapse of unconsolidated formations can result in decreased flow and production, increased erosion of well components, and production of well sand which is a hazardous waste requiring specialized handling and disposal. Such gravel packing typically involves depositing a quantity, or xe2x80x9cpack,xe2x80x9d of gravel around the exterior of a perforated pipe and screen. The gravel pack then presents a barrier to the migration of the sand while still allowing fluid to flow from the formation. In placing the gravel pack, the gravel is carried into the well and into the formation in the form of a slurry, with much of the carrier fluid or workover fluid being returned to the surface, leaving the gravel in the desired location.
An increasingly popular technique to complete wells with sand control problems is an open hole gravel pack. However, to successfully complete an open hole gravel pack, it is often necessary to maintain good mudcake integrity in the open hole interval. This can be accomplished by maintaining an overbalance condition in the wellbore with respect to the reservoir adjacent the wellbore. An overbalance condition exists when the pressure within the wellbore is higher than the reservoir pressure.
However, many conventional gravel pack service tools used for performing gravel pack in an open hole section of a wellbore tend to swab the open hole section as the service tools are moved to various positions during a gravel pack operation. Swabbing occurs as a service tool is pulled up while various seals of the service tool remain engaged (such as seals within seal bores and packer seals against the inner surface of the wellbore). The swabbing effect causes pressure in the open hole section of the wellbore below the seals to drop. If the drop in pressure is high enough, then the pressure in the open hole section may drop below the reservoir pressure, thereby causing the overbalance condition to be removed. When the overbalance condition no longer exists in the open hole section of the wellbore, reservoir fluids can start flowing into the wellbore, which may cause damage to the mudcake. Once the mudcake is damaged, fluid loss from the wellbore to the reservoir may occur when the pressure in the open hole section is again restored to the overbalance condition. In some cases, such fluid loss can be great enough to prevent successful gravel packing of the interval.
A need thus exists for an improved method and apparatus of gravel packing an open hole section of a wellbore.
A method for use in a wellbore includes performing a gravel pack operation with a tool assembly in a section of the wellbore and providing a bypass mechanism in the tool assembly. The bypass mechanism is actuated using a remote signal, and communication of an elevated pressure is maintained through the bypass mechanism to the wellbore section to provide an overbalance condition in the wellbore section.
Other or alternative features will become apparent from the following description, from the claims, and from the drawings.